New Grower ph help please asap

[jamesbrown69]

i checked the run off of my soil using the liquid drops that come with the ph up and down and it comes out red like if it was around 4.0 what do i do i was puttin in 6.5 water in should i go higher on the ph till i get a run off of 6.5?
happyfrog soil

 

[turtle360]

I am a new grower (zero completed grows) so I don't have an answer based on empirical evidence, but I had a similar experience. I use soil and applied 6.5 ph adjusted water w/ Big Bloom and got a 5.8 runoff. I scrounged around for answers and came up with:

From Fox Farm: What matters most is the ph of what you put in. The runoff ph does not yield valuable information. In fact only water till runoff starts then stop watering; you should not even have enough to ph test.

From General Hydroponics who I called to find out if I could test my soil ph with the kind of kit you have: What matters most is the ph of what you put in. If what you put in is right you should not have a problem. The runoff ph does not yield valuable information. The runoff picks up minerals and what not that changes the ph. Water till you get 15-20% runoff.

From the peanut gallery:You can extrapolate your soil ph by using the input and output. Thus, if you water with 6.5 and runoff is 6.0 your soil ph is 5.5. Not sure if that's so. Then your soil ph would be 1.5.

But you could get a fairly inexpensive probe and see what it says.

 

[az2000]

i checked the run off of my soil using the liquid drops that come with the ph up and down and it comes out red like if it was around 4.0 what do i do i was puttin in 6.5 water in should i go higher on the ph till i get a run off of 6.5?
happyfrog soil

What do your plants look like? You can cultivate 1/2 tsp dolomite lime into the 1/2" topsoil (using a kitchen fork as a rake) and let it water into the soil. I don't know the acceptable amount to add in total, but you could do that 2-3 times I think. It should be very fine dolomite, not the pelletized stuff. (You can crush coarse dolomite in a mortar/pestel, but be careful not to breath the dust.).

Dolomite is slow-acting, and only goes to about ph 7 (relatively safe). Hydrated (Ca(OH)2) or quick (CaO) lime is faster acting and is very potent, can go into the ph 10 range. I wouldn't use it unless you're plant is exhibiting a serious problem.

Do you water/feed with 20% runoff? If not, and you're a few weeks into the grow you may have salt buildup. Maybe a good flush is called for.

I'm facing the same thing you are, and seeing a magnesium deficiency. I'm going to water with some "Hi-Yield Horticultural Hydrated Lime" -- enough volume for 50% runoff. (I think a true flush is supposed to be 200% runoff. But, I've gotten some good runoff at times during this grow. So, I don't think I have a serious salt buildup. I think something went awry with my medium. Maybe didn't use enough dolomite when I mixed it.).

I'm considering 1/2 tsp in 1.5 gal, poured into a 3gal pot. I've read people using 1tsp. But, I've been foliar feeding with 1/2 tsp in a pint (1tsp per qt) Epsom Salt. I don't want to go overboard correcting a problem I can compensate for with foliar feeding. I'd rather do hydrated lime in 2-3 doses than overdo it in one shot.

I believe it's generally discouraged to do what I'm doing. But, I like learning as much as I like finishing a successful grow. So... I'm ok if it doesn't turn out well.

PS, I agree with turtle. I'm very perplexed by the topic of soil ph. I've seen low ph in runoff and my plants didn't exhibit a problem. Now, I've got a serious problem (which may be attributable to my switch to an LED). I have an Accurate 8 soil probe ($60, the same as Muddy uses). I get different readings in different locations. The probe doesn't always agree with the runoff. (Muddy says he trusts the probe, not the runoff.).